Sixth-form heads believe young people needed to be tutored as early as year 7 in how to formally credit and reference sources, says Barry Calvert. Photograph: Guardian

The number of schools using plagiarism-detecting computer software to catch A-level students cheating in their coursework has rocketed, amid warnings that children as young as 11 need to be taught not to copy and paste from the internet.

Nearly 90 schools and more than 130 colleges now use the Turnitin database to cross-check pupils' work with material found online – double the numbers two years ago.

Barry Calvert, of nLearning, which provides the software, said sixth-form heads believed young people needed to be tutored as early as year 7 in how to formally credit and reference sources, rather than just taking chunks of text off the internet and passing it off as their own.

The figures come at the beginning of a three-day international conference into plagiarism at Northumbria University, where experts from around the world will share ideas for catching cheats. The conference, organised by the nLearning-funded Plagiarism Advice Service, will hear how new research suggests that half of university students would be prepared to submit essays bought off the internet.

Dan Rigby, an economics lecturer at Manchester University, questioned 90 second- and third-year students at three universities and found they would be prepared to pay more than £300 for a first-class essay, £217 for a piece of work worth a 2:1 and £164 for a 2:2.

Rigby said: "Although the sample of students is small, the results are indicative, statistically robust and rather disturbing." He also found that 45% of students were certain a peer had cheated during an essay, report, test or exam in the past year.

Earlier this year the exams regulator, Ofqual, revealed that an increase in the number of pupils trying to cheat in their GCSEs and A-levels using mobile phones and MP3 players led to penalties for malpractice rising by 6% in a year.

Students received more than 4,400 penalties in 2009, and the number handed out by staff was up 29%.

Most universities in the UK already use Turnitin, but are telling school heads it is their responsibility to teach students referencing skills, Calvert said. "There's been a lot of push back from higher education saying it's up to schools to have children prepared when they come to us so they understand how to do this," he said.

"We need to get students to understand that the internet is not just some kind of information smorgasbord you can turn to – it's actually somebody's work that needs to be credited and sourced in the same way as you would other sources," he said.

But the internet also has a positive effect on learning, Calvert added.

"When I was a child our local library used to be sick of the sight of us saying 'has that book come back yet?' because there was only one book on the Vikings or the Romans. So on the one hand the internet has opened up a greater opportunity for everybody to learn, but on the other it's created that opportunity for people to just cut and paste."

The conference will also hear that the problem of plagiarism at university could be reduced if students used "digitial storytelling" – creating packages of images and voiceovers – rather than essays to explain their learning from an imagined personal perspective.

Phil Davies, senior lecturer at Glamorgan university's computing school, said he had been using the technique for two years and had not seen any evidence of cheating. "Students find it really hard but it's very rewarding, because they're not copying and writing an essay, they have to think about it and bring their research into a personal presentation."